Abscisic Acid Accumulation in Developing Seeds of Phaseolus vulgaris L

Abstract

Free and bound abscisic acid (ABA) in the pod, seed coat, and embryo were determined separately throughout seed develpment of Phaseolus vulgans L. cv. 'Taylor's Horticultural.' An internal standard method of gas-lquid chromatography was used for ABA quantification. In the embryo, two peaks of free ABA occurred at days 22 (1.18 micrograms per gram or 5.5 micromolar) and 28 (1.74 micrograms per gram or 12 micromolar); and a single peak of bound ABA at day 30. In the seed coat, there was one peak of free ABA at day 22 and only small amounts of bound ABA. Very small amounts of ABA were detected in the pod at any stage of development. In cv. PI 226895, in which seed development is more rapid than in 'Taylor's Horticultural,' the embryo ABA peaks occur on days 20 and 26. The timing of the ABA peak in the embryo, and the concentration attained, are consistent with previous reports on the natural pattern of RNA synthesis and with ABA inhibition of RNA synthesis in developing bean fruit.Developing fruits and seeds have long been known as a rich source of plant hormones (14). In many species, changes of hormone content throughout development of the reproductive parts have been determined. From the accumulated data, there appears to be a general pattern of high growth promoter content in early development followed by high inhibitor, mainly ABA, content later in development (1,6,14). This late appearance of ABA has been thought to have important implications in fruit maturation (2), abscission (3), or seed dormancy (5).This report is an analysis of the change in ABA content during reproductive development of Phaseolus vulgaris, with a discussion of its correlation with seed weight changes and other related processes. P. vulgaris was chosen because of the large body of information on reproductive development (9, 24), macromolecular metabolism (21, 23), and genetics (28). Clarkson Chemical Co., Williamsport, Pa.) was suspended in chloroform and packed in a 5-ml glass disposable pipette which was plugged with a piece of glass wool at the outlet. ABA extracts were dissolved in chloroform and loaded into the column. The column was eluted first with 10 ml of chloroform to wash off some impurities. It was next eluted with 10 ml of chloroform-methanol (90:10). This fraction contained ABA, and was saved for derivatization. A small scale method was used to generate diazomethane which derivatized ABA into its methyl ester (19).A Hewlett-Packard model 1610A gas chromatograph equipped with a flame ionization detector and an automatic peak area integrator was used throughout ABA quantification. An XE-60 column was used for all samples. OV-I and OV-17 columns were used to verify the authenticity of any suspect ABA peaks. A suspect peak was confirmed as c-t ABA if it co-chromatographed with authentic c-t ABA in all three columns. Operating conditions were: column temperature, 200 C; injector and detector temperature, 250 C; carrier gas (N2) flow rate, 40 ml/min.Tetraphenyl ethylene was used as an internal standard to facilitate th...

Abscisic Acid and Its Relationship to Seed Filling in Soybeans

“…However, King and Patrick (12) saw no stimulation of 14C transport to wheat ears after injection of ABA into the grains. Correlations between rate of growth and ABA accumulation in major sinks have been reported for wheat (13,14), grapes (5), pea (3), bean (10), and soybeans (4,15). The relatively high levels (up to 12.2 #g g-' fresh weight) (15) and timing of ABA accumulation in soybean seeds (1,4,15) suggest a role in seed growth above simply preventing precocious germination.…”

Distribution of Abscisic Acid in Maize Kernel during Grain Filling

“…The level of ABA in seeds has been found to increase during development usually coincidently with accumulation ofdry mass and reaches a maximum prior to physiological maturity (8,11,13,16,17). Typically, the ABA concentration in cereals is generally lower than found in legumes (8, 11, 13 16, 17).…”

“…the sink strength of kernels), which may be under hormonal control. ABA has been implicated in the regulation of sink strength in small grains (2,11,13,16,22), soybeans (17), and some horticultural crops (3,8,14,25,26) through mediation of phloem unloading. Similar information has not been reported for maize.…”

Etude histologique des embryons avortés lors des croisements entre <i>Phaseolus vulgaris</i> L. et <i>Phaseolus coccineus</i> L.

“…Elles y assurent la synthèse et l'approvisionnement de l'embryon en éléments nutritifs. Il est cependant nécessaire d'identifier et d'apprécier la nature des nutriments qui transitent par ce canal en dehors des hormones de croissance car les molécules de masse légère (les glucides) n'ont pas la même facilité de transfert que les molécules lipidiques ou protidiques (Hsu, 1979;Yeung et Clutter, 1979;Picciarelli et Alpi, 1986;Piaggesi et al, 1989;Perata et al, 1990).…”